code: def scale(self, loss):
      return loss
  
file_path: sru/test/test_amp.py
imports: import pytest
  import sru
  from typing import Any
  import time
  import torch
  from torch import optim
  import contextlib
label_desc: Use image node_id 1 for calling the NullGradScalar obj's underlying member method code with example usage: obj.scale(loss) and returns: loss